Electrostatic precipitators are commonly used in the power generating industry to remove certain unwanted particulate from exhaust gases. In the typical construction of an electrostatic precipitator, a plurality of long flat collector plates are hung within a chamber. Electrode wires or rigid frame electrodes are positioned between the plates. An electrostatic charge is generated between the wires and the plates, so that particulate matter is charged on the wires and is collected on the collector plates. The collector plates may have a length of from 20 feet to 50 feet, depending upon the capacity of the particular precipitator. The typical collector plate is generally flat and has edges which are folded in order to stiffen the plates. The plates are secured to hangers, which hangers in turn are hung on beams. The collector plates are usually fabricated from a roll of a cold rolled steel. Fabrication of the collector plates includes flatening the cold rolled steel. Sometimes, this process is imperfect and the collector plates are fabricated with a bow in them. Sometimes, when the collector plates are hung, the plates tend to bow also. It is desirable to have a uniform spacing from each plate to the electrode wires. Obviously, if the wires are straight and the plates are bowed, the spacing is not uniform. It follows that it is desirable to straighten the plates.
A present accepted method of straightening the long plates is to heat and quench selected portions of the plates after they have been hung, and depend upon the expansion and contraction of the metal to straighten the plates. The common method of heating the plates is to use torches to apply heat to specific areas of each plate. Since the specific area to be heated, the amount of heat required, the area to be quenched and the degree of quenching required is a matter of judgement, the results depend upon the skill and experience of the workman. It is unusual to successfully straighten plates utilizing this method and it requires considerable man hours of effort. Many times, the effort results only in collector plates that are more distorted than prior to the heating and quenching operation. It has also been found that a problem sometimes developes in that the plates which have been straightened utilizing the heat and quenching method become bowed in another direction after a short period of time.
It is known to provide a precipitator construction wherein the precipitator plates are held at both the top and the bottom. This construction is taught in U.S. Pat. No. 3,892,545, issued July 1, 1975, entitled, "Arrangement For Suspending And Controlling Precipitation Electrodes". The inventor is Rolf Goransson, of Vaxjo, Sweden. Holding the plates at the top and at the bottom still does not prevent the center from bowing, which gives the non-uniform spacing between the electrode wires and the collector plate.